A new documentary claims that American rap mogul P Diddy had Tupac Shakur shot to death as the star rapper drove with his manager Marion (Suge) Knight down a Las Vegas street. The 1996 murder of Shakur remains officially unsolved to this day.

It was widely viewed at the time as a violent confrontation between coastal rap fiefdoms. Suge Knight ran Death Row Records representing West Coast rappers while Diddy had launched Bad Boy Entertainment on the East Coast.

The documentary, Murder Rap, is based on a 2011 book by the same name written by former Los Angeles detective Greg Kading, who headed the Los Angeles Police Department task force investigating the killing. He alleges that Sean (Diddy) Combs, formerly known as Puff Daddy, offered Crips member Duane Keith (Keffe D) Davis $1m (£690,000) to "whack" Shakur and Knight.

Davis' nephew, Orlando (Baby Lane) Anderson, eventually pulled the trigger in a drive-by shooting, Kading claims in the upcoming Netflix film. Shakur was fatally injured and died six days later; Knight was injured but survived.

There was no immediate response from Diddy, but when Kading's book was first published he called it "pure fiction and completely ridiculous." Kading said he wrangled a confession out of Keffe D after the Crips member feared facing charges for a different crime.

The detective was convinced Keffe D was telling the truth when he admitted to the crime. "What really convinced us it was true was all the corroboration," Kading told the New York Daily News. "He told us things that he couldn't known unless he was actually a participant in the murder." He knew, for example, that there was a related shooting that night that investigators had kept a secret, according to Kading.

Kading believes the shooting was a "preemptive strike" by Diddy, who feared he would be murdered by Knight, who held Diddy responsible for the earlier death of a friend. "There was a very clear and present danger," said Kading. Diddy is "not a calculating, sinister assassin, but a person trying to protect himself from something he knew was coming."

Six months after Shakur's death, Biggie Smalls — a close pal of Diddy's — was shot dead on a Los Angeles street. Kading believes Knight hired a hitman to kill Smalls in retaliation against Diddy for Shakur's death. Knight, 50, is currently being held in Los Angeles soon to face trial on charges of murder and attempted murder in an unrelated case.

No one was charged in the murders of Shakur or Smalls and the investigations were dropped after law enforcement officials successfully fought a wrongful death suit by Smalls' mother claiming a police officer was involved in her son's death. Kading believes the department was more interested in defending itself against the lawsuit than seeing the murder investigations through. The department was also reluctant to take on a celebrity like Diddy, said Kading.